Piezoelectric　ceramic　wafers　are　applied　for　the　excitation　and　detection　of　ultrasonic　guided　waves　to　determine　the　health　state　of　plate-like　structures.　Two　PZT　wafers,　whose　diameter　is　11mm　and　thickness　is　0.4mm　respectively,　are　bonded　permanently　on　the　surface　of　a　1mm　thick　aluminum　plate.　One　of　these　wafers　is　actuated　by　sinusoidal　tone　burst　at　various　frequencies　ranging　from　100kHz　to　500kHz,　the　other　one　is　used　as　a　receiver　for　acquiring　ultrasonic　guided　wave　signals.　According　to　the　amplitudes　and　shapes　of　these　received　signals,　guided　wave　modes　and　their　proper　frequency　range　by　using　these　wafers　are　determined.　For　the　improvement　of　the　signal-to-noise　ratio,　the　Daubechies　wavelet　of　order　40　is　used　for　signal　denoising　as　the　mother　wavelet.　Furthermore,　the　detection　of　an　artificial　cylindrical　through-hole　defect　is　achieved　by　using　S0　at　300kHz.　Experimental　results　show　that　it　is　feasible　and　effective　to　detect　defects　in　plate-like　structures　based　on　ultrasonic　guided　wave　technology　by　using　bonded　piezoelectric　ceramic　wafers.　©　2009　SPIE.